Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque

H, W = map(int, input().split())
s = [list(input()) for i in range(H)]

q = deque([(0, 0, 1)])

while q:
  h, w, c = q.popleft()
  if s[h][w] != ".": continue
  s[h][w] = c
  if h+1 == H and w+1 == W: break
  if 0 <= h-1: q.append((h-1, w, c+1))
  if h+1 < H : q.append((h+1, w, c+1))
  if 0 <= w-1: q.append((h, w-1, c+1))
  if w+1 < W : q.append((h, w+1, c+1))
else:
  print(-1)
  exit()

print(H*W - sum([sum([x == "#" for x in sh]) for sh in s]) - s[-1][-1])